Electrical relay



April 30, 1940. 8 W 2,198,704

ELECTRICAL RELAY Filed June 8, 1937 2 Sheets-Sheet l INIV OR IIZS ATTORN EY April 30, 1940.

B. LAZICH ELECTRICAL RELAY Filed June 8, 1937 H15 ATTORNEY 2 Sheets-Sheet 2 w .55 lNV TOR Patented Apr. 30, 1940 UNITED STATES ELECTRICAL RELAY Branko Lazich, Pittsburgh, Pa, assignor to The Union Switch & Signal Company, Swissvale, Pa., a corporation of Pennsylvania Application June 8, 1937, Serial No. 146,997

11 Claims.

My invention relates to electrical relays.

One object of my invention is to provide a compact type of neutral relay suitable for use in railway signaling systems.

Another object of my invention is to provide a relay of such construction that it can be readily connected with or disconnected from its external circuit connections.

A further object of my invention is to provide a relay which can be constructed at a minimum cost, but which at the same time is highly efficlent for its intended purpose.

Other objects and characteristic features of my invention will appear as the description proceeds.

' I shall describe one form of relay embodying my invention, and shall then point out the novel features thereof in claims.

In the accompanying drawings, Fig. 1 is a front elevational view showing one form of relay em- 29 bodying my invention. Fig. 2 is a back view of the relay shown in Fig. 1, certain of the parts being removed to better illustrate the construction of the remaining parts. Fig. 3 is a sectional view taken approximately on the line III-III of Fig. 1. Fig. 4 is a top plan view of one of the movable contact fingers 35 forming part of the contact mechanism of the relay. Fig. 5 is a top plan View of one of the front contact fingers 36 forming part of the contact mechanism of the relay. Fig. 6 is a top plan view of one of the back contact fingers Bl forming partof the contact mechanism of the relay.

Similar reference characters refer to similar parts in each of the several views. Referring to the drawings, the relay comprises two magnetizable pole pieces I secured, as by riveting, to a non-magnetizable supporting bracket 2, which supporting bracket, in turn, is fastened by means of screws 3 to a backplate 4 of suitable insulating material that can be readily moulded, such for example, as a phenol condensation product. The pole pieces I extend upwardly through slots 5 formed in the bracket 2, and are provided at their upper ends with outwardly extending portions l A magnetizable backstrap 6 is secured at its ends to the outwardly extending portions I of the pole pieces I by means of screws 1, and mounted on this backstrap is an insulating spool 8 carrying a winding 9 for supplying magnetic flux to the pole pieces I. The portions of the pole pieces which are located on the underside of the bracket 2 extend toward each other, and have their lower or pole faces ground to lie in the same plane. The spool 8 is of moulded insulating material,

and as shown in Figs. 1 and 3, the one head 8 of this spool is provided on its outer side with an integral lateral extension 8 having two vertically disposed tapped threaded inserts 8 and 8 moulded therein adjacent its opposite ends. 5 A groove 8 which extends parallel to the longitudinal axis of the spool is formed in the lateral extension 8 directly above the insert 8, and the inner end of this groove communicates with another groove 8 which extends downwardly at 10 right angles to the groove 8 and then inwardly at right angles to the axis of the spool to the inner end of the head 8, and disposed in the grooves 8 and 8 is a flat metal strip 9 which is bent to lie flat in the grooves 8 and 8 in the manner shown. The strip 9 comprises one terrninal for the winding 9, and the inner end of this strip is disposed underneath the first few turns of the winding 9 and is soldered thereto, while the outer end of this strip is formed with a hole which aligns with the tapped hole in the associated metal insert 8. Another groove 8 similar to the groove 8 is formed in the extension 8 directly above the insert 8 and disposed in this latter groove is another fiat metal strip 25 9 which constitutes the other terminal for the windings. The inner end of this latter strip is wound under the last few turns of the winding 9 and is soldered thereto, while the outer end of this strip is provided with a hole which aligns with the tapped hole in the metal insert 8.

Formed in the backplate 4 directly back of the grooves 8 and 8 in the spool 8 are two rectangular slots 4 which communicate at their inner ends with rectangular recesses 4 provided in the- 36 backplate directly behind the slots, and disposed in these recesses are female connectors I0 having tail portions Ill which project through the slots II and are clamped against the upper sides of the strips 9 and 9* by means of studs II screwed into the inserts 8 and 8 respectively. Each female connector, as here shown, is constructed of a single piece of metal bent over onto itself to form the tail portion I0 and is provided at its ends with spaced U-shaped return bends the 45 inner legs of which are urged together due to their inherent resiliency. The connectors are held in place in the recesses 4 and slots 4* by means of a cover plate I2 of insulating material which is secured by means of screws I3 within a recess 4 provided in the rear face of the backplate 4. The screws I3 pass through circular offset portions I2 formed in the cover plate I2 and are screwed at the inner ends into tapped metal inserts I4 moulded into the backplate 4. 66

The female connectors III are adaptedto cooperate with suitable male connectors which will be described hereinafter for making external connections with the winding 9, and formed in the cover plate in alignment with the female connectors are suitable slots l2 for the reception of the plug portions of the male connectors.

The relay also comprises a magnetizable armature i5 which is pivotally supported for swinging movement toward and away from the pole faces l of the pole pieces i. As here shown, the means for pivotally supporting the armature includes a non-magnetizable bracket I! which is secured to the underside of the armature at its rear end, and which is provided at each side of the armature with an ear ll bent at right angles to the body of the bracket. The ears l1 extend rearwardly from the armature between two pairs of spaced depending lugs 2 formed on the bracket 2, and are pivoted on a rod 18 mounted in the lugs 2 The rod I8 is preferably of phosphor bronze, and is held in place by splitting its ends and bending them outwardly in a wellknown manner,

The attracted or energized position of the armature l5 is limited by a core pin l9 oi nonmagnetizable material which is riveted to the armature adjacent its forward end, and which cooperates with the head of one of the rivets which secure the pole pieces I to the bracket 2, while the released or deenergized position of the armature is limited by a stop screw 20 adjustably mounted in a supporting strap 2| secured to the underside of a depending portion 2 formed on the front end of the bracket 2. An auxiliary core pin I9 is also riveted to the armature l5 adjacent its rear end in a position to engage the head of another one of the rivets which secure the pole pieces I to the bracket 2. This latter core pin is made shorter than the first mentioned core pin, and is provided to prevent the armature from touching the pole pieces in the event that the first mentioned core pin becomes worn. The stop screw 20 is arranged to be locked in an adjusted position by means of a lock nut 22. The pole faces l will preferably be covered with lacquer or'plated with suitable plating material to prevent them from rusting or corroding, while the heads of the rivets with which the core pins 19 cooperate will be kept clean, and it will be apparent, therefore, that there is no danger of the armature sticking in its attracted position due to the core pin engaging the rust preventative substances. I V

The bracket II, in addition to being provided with the rearwardly extending ears l'l which support the armature, is also provided with two arms ll which project outwardly beyond the opposite sides of the armature. Formed in these arms are screw threaded holes l'l which align vertically with recesses 23 formed in the underside of the supporting bracket 2, and adjustably mounted in the holes i1 are spring guides 24, the upper ends of which extend partway into the recesses 23 with considerable clearance. The spring guides are provided intermediate their ends with shoulders 24 which are made polygonal in shape to facilitate adjusting the guides, and surrounding the guides above the shoulders 24'- are compressed coil springs 25 which assist the force of gravity in biasing the armature to its released position. It will be apparent that by adjusting the vertical positions of the guides, the tension of the springs may be varied, thereby providing a convenient means for varying the force with which the armature is biased to its released position. The guides 24 are adapted to be locked in their adjusted positions by means of lock nuts 26 which are screwed onto the lower ends of the guides.

Secured to the underside of the armature II intermediate its ends, by means'of screws ll, is a bracket 3| provided at each end with a pair of depending lugs II in which a rod 32 of suitable material such as phosphor bronze is mounted,

and pivoted on the rod 32 between each pair of lugs is a depending contact operating member 33 of moulded insulating material. Each contact operating member 33 extends downwardly between two vertical rows of contacts, each row of which comprises two vertically spaced movable contact fingers 35 disposed between a cooperating front contact finger 38 anda cooperating back contact finger I1, and is operatively connected intermediate its ends with the movable contact fingers on each side thereof iritermediate their ends by means of laterally projecting arms 33" between which the movable contact fingers extend. As will be seen from the drawings, the arms 33 are disposed in oppositely extending pairs and have their surfaces on the side adjacent the associated finger rounded to prevent wear on the arms or the fingers in response to the movement of the armature. It is desirable that the contact operating members should move in a fixed path in response to the movement of the armature, and to this end the lower end of each contact operating member is secured by means of a stud 33 moulded into the operating member to the outer end of a flexible guide strip 30, the inner end of which strip is secured by means of a screw 39 to a supporting strip III. Each supporting strip 40 is formed with a portion 40' of reduced width which extends through an opening 4* comprising one of a plurality of similar openings formed in a raised portion 4' moulded onto the backplate, and each strip 40 is secured to the backplate by bending portions of the end of the strip outwardly on the rear side of the backplate by means of a suitable swedging tool. The rear portion of each opening 4 is made the same shape as the reduced portion 40 of the associated strip 40 to prevent the strip from turning and to insure that the strip will be securely held in place, but the outer end of each opening is provided with rounded portions to facilitate moulding the openings into the backplate.

The movable contact fingers 35 are all alike, and as shown in Figs. 3 and 4, each finger 35 comprises a flexible strip 35 of suitable conducting material, such as phosphor bronze, provided at its front end with low resistance contact members 35* consisting in the particular embodiment illustrated of U-shaped strips of silver or silver laminated material riveted to the opposite sides of the flexible strip 35. Each finger 35 also comprises a rigid strip 35 which is riveted to the rear end of the strip 35', and which is crimped in a longitudinal direction to form a rib which stifiens the strip. The rear end of each rigid strip 35 is formed with a portion 35 which is narrower than the body of the strip, and which forms two shoulders 35, and with another portion 35 which is narrower than the portion and which forms two shoulders 35'. The portion 35 of each strip is inserted into an associated one of the openings 4 provided in the raised portion 4 of the backplate 4 to such a position that the shoulders 35 engage the front face of the raised portion 4', and the opposite edges of the strip are then bent outwardly at the shoulders 35' by means of a swedging tool, whereby each finger 35 is firmly secured to the backplate. The rear end portion 35 of each strip projects into a rectangular recess 4 formed in the rear face of the backplate 4 directly behind the raised portion 4', and constitutes a plug for making connection with a suitable female connector comprising part of a plug receptacle provided on a supporting plate 4|, as will be described more fully hereinafter. The tip of each portion 35' is rounded for obvious reasons.

The front contact fingers 36 are likewise all alike, and as shown in Figs. 3 and 5 each of these fingers comprises a rigid conducting strip 36 provided at its outer end with a low resistance contact member 36 which in the particular em- *bodlment illustrated comprises a carbon block.

Each strip 36"- is crimped longitudinally to form a stiffening rib, and is provided at its rear end with portions 35 and 36 of reduced width similar to the portions 35 and 35 of the strip 35 of the finger 35. Each portion 36 projects through one of the slots 4 in the backplate, and is secured to the backplate in the same manner that the strips 35 of the fingers 35, and the strips 40 are secured to the backplate. The reduced portion 36 of each strip comprises a plug for making contact with the associated finger, as will appear more fully hereinafter.

Each back contact finger 31 comprises a flexible strip 31 which is somewhat stiffer than the strip 35 of the finger 35 provided at its outer end with a low resistance contact member 31 comprising in the embodiment illustrated a U- shaped strip of silver or silver laminated material riveted to the upper side of the strip 31*, each U-shaped strip being formed with a flat top. The rear end of each strip 31" is secured to a rigid strip 31 which is identical in construction to the rigid strip 35 of the movable finger 35, and which is secured within one of the holes 4 in the same manner that the strips 35 are secured within the associated holes 4. The rear end portion 31 of each strip likewise comprises a plug for making external connection with the associated back contact finger.

The parts are so proportioned that when the armature occupies its midstroke position, the movable contact fingers 35 will all occupy positions in which they are unstressed, and in which the low resistance contact members 35'" are dis posed midway between the low resistance contact members 36 and 31 of the associated front and back contact fingers 36 and 31, but that, when the armature is moved to its upper position, the

fiexibleportions of the movable fingers 35 will then be bent upwardly through'the medium of the contact operating member 33 to positions in which the upper low resistance contact members 35 will engage the low resistance contact members 36 of the front contact fingers 36 to close the front contacts 3535 of the relay, and that, when the armature is moved to its lower or retracted position, the flexible portions of the movable fingers 35 will then be bent downwardly through the medium of the movable contact fingers 35 to lower positions in which the low resistance contact members 35 will engage the low resistance contact members 31' of the back contact fingers 31 to close the back contacts 35-31 of the relay. It will be seen, therefore, that the front contacts or the back contacts of the relay will be closed according as the winding 9 isenergized or deenergized.

All of the operating parts of the relay are enclosed within a cover 45 of moulded glass or other transparent material, which cover is'secured to the bracket 2 by means of studs 46, and which engages at itsrear edge a suitable gasket 41 secured to the forward face of the backplate adjacent its outer edge. The cover 45 protects the operating parts from dust or other foreign substances, and at the same time permits ready inspection of these parts without necessitating the removalof the cover.

The entry of foreign substances around the openings 4* in which the various contact fingers are mounted is prevented by a rubber gasket 49 which is disposed in the bottom of the recess 4, and which is held in place by a clamping plate 50 of suitable insulating material secured to the backplate by means of screws 5|. The gasket 49 and clamping plate 50 are provided with aligned openings through which the plug portions of the various contact fingers pass, and it will be apparent that when the screws 5| are tightened, the rubber gasket 49 will become compressed, thus providing an effective seal around the plug portions of the contact fingers at the point where the plug portions emerge from the backplate. The screws 5| pass through clearance holes in the clamping plate, and are screwed into threaded inserts moulded into the backplate.

It is desirable to be able to quickly connect a relay of the type described with, or disconnect it from, all external circuit connections, and to this end the previously referred to mounting plate 4| is provided. This plate, which is of moulded insulating material, is adapted to be secured-to any suitable support in a vertical position, and is provided adjacent each corner with a hole 4| for the reception of bolts or other securing means. Moulded into the mounting plate 4| adjacent its upper ends are spaced connectors 55, the forward ends 55 of which project outwardly from the mounting plate for some distance and constitute plugs which, when the relay is mounted on the mounting plate in the proper position, extend through the slots |2 in the cover plate l2 and make contact with the female connectors l0, and the rear ends 55 of which project beyond the back of the mounting plate and constitute 1 terminals to which the external circuit wires comprising the energizing or the control circuit for the winding 9 may be secured in any convenient manner, as by soldering.

Formed on the mounting plate directly opposite the recess 4 in the backplate is a raised portion 4 which is adapted to fit into the recess 4 when the relay is mounted on the mounting plate, and provided in this raised portion are a plurality of slots 4| each of which is adapted to receive the rear end or plug portion of an associated one of the contact fingers 35, 36, or 31 with some clearance. The slots 4| each communicate with a recess 4| formed in the panel directly behindthe slot, and mounted in each recess is a female connector 56 similar to the previously described connector I0, which connectors are adapted to engage the plug portions of the fingers, and thereby make electrical contact there with, in the manner shown in Fig. 3. The female connectors 56 are held in place within the recesses 4| by means of a retaining plate 51 which fits into a recess 4| formed in the rear face of the mounting plate, and which is provided with a plurality of slots 51 through which the tail portions of the connectors extend. The retaining plate 51 is secured in place in the recas 41' by means of screws 58 which pass through clearance holes in the plate, and are screwed into threaded inserts moulded into the backplate. The tail portion of each female connector projects through the retaining plate far enough to permit circuit wires to be readily soldered or otherwise secured thereto, and constitutes a terminal for the reception of the circuit wires. It will be apparent that the raised portion 4| of the mounting plate, together with the associated connectors and other parts, constitute the plug receptacle referred to hereinbeforc, whereby external electrical connections between the contact fingers of the relay and the external circuit wires which are adapted to be connected with these fingers may be quickly made.

Also moulded into the mounting plate is a latching member 60 comprising part of suitable latch mechanism for securing the relay to the mounting plate. As here shown, this latching mechanism is in the form of a projecting post having a conical head 60 the rear side of which forms an annular shoulder 60''. The latching member is adapted to extend with clearance through a hole I2 formed in the cover plate l2, and cooperates with a latch spring 6| disposed in the recess 4 provided in the backplate. As best seen in Fig. 2, the latching spring BI is provided with two upwardly extending arms 6| and Gi and is secured at its lower end to the backplate by means of an L-shaped bracket 62, and the lower one of the screws 3 which fastens the bracket 2 to the backplate. The arms GI and 6! are biased toward each other to such positions that when the relay is in place on the mounting plate, these arms will embrace the opposite sides of the latching member directly back of the shoulder formed by the head 60 in such manner that the relay cannot be moved away from the backplate without first separating the arms to positions in which they are clear of the head. To facilitate separating the arms, the upper ends of the arms are bent inwardly and then outwardly to form cam surfaces ti and cooperating therewith is a cam member 63 provided with a U- shaped annular groove 63. The cam member 63 is secured to a rod 64 which extends upwardly through a clearance hole 65 formed in the backplate 4, and is provided at its upper end with a knob 66 by means of which the rod 64 may be moved upwardly. The rod 65 and associated parts are biased by means of a spring 61 to a r lower position in which the knob 66 engages the upper edge of the backplate, and the parts are so proportioned that when the rod occupies its lower position, the cam surfaces 6i on the arms 6i and 6| of the latch spring 6! will extend into the V-shaped groove 63 in the cam member 63 with sufficient clearance to permit the arms to move to their latching positions, but that, if the rod 64 is moved upwardly, the cam member will cooperate with the cam surfaces 6| to spread the arms 6| and 8| to positions in which they are clear of the shoulder 60 on the latching member 60.

With the relay and associated mounting plate constructed in the manner described, it will be apparent that the relay can be secured to the mounting plate by merely pushing it toward the mounting plate to the position in which the rear face of the backplate of the relay engages the forward face of the mounting plate, and that when this is done, the latch mechanism will act to automatically latch the relay in place on the mounting plate. It will also be apparent that when the relay is secured to the mounting plate, the leads of the winding I will become automatically connected with the connectors 55, and g the contact fingers 35, 38 and 31 will become automatically connected with the corresponding female connectors 56 of the plug receptacle, so that if the proper circuit connections have been made to the coil connectors 55 and the various 10 female connectors, the relay will become automatically connected with its control and controlled circuits. It will also be apparent that if it is desired to disconnect the relay from its external circuit connections at any time, this may 15 be quickly and conveniently done by merely lifting the knob 66 to operate the latch mechanism to its unlatched position, and then pulling the relay laterally away from the mounting plate.

When the relay has been removed from the 1.7

mounting plate, a similar relay can be immediately attached to the mounting plate, thereby avoiding any extended interruptions in the operation of the circuits controlled by the relay.

It should be noted that when the relay is being moved toward the mounting plate to secure it to the mounting plate, the connectors 55 act as guides for the relay.

It should also be noted that while in describing my invention, I have shown only one contact-30 combination, other contact combinations may be readily obtained by assembling the various contact fingers in different positions. For example, if all front contacts are desired, these may be obtained by placing front contact fingers 38 in 35 the second and fourth holes 4 from the bottom of each row of holes, as viewed in Fig. 1 in place of the movable contact fingers 35 and back contact fingers 31 shown in the drawings, and by placing movable contact fingers I! in the lower- 4i hole and third hole from the bottom of each row of holes in 'place of the back contact fingers 31 and front contact fingers 36 shown in the drawings, and then replacing the contact operating members 33 with other contact operating 4| members having six pairs of laterally projecting arms 33" instead of four pairs. The manner in which other contact combinations may be obtained will readily suggest themselves to any one skilled in the art.

Although I have herein shown and described only one form of relay embodying my invention, it is understood that various changes and modifications may be made therein within the scope of the appended claims without departing from the spirit and scope of my invention.

Having thus described my invention, what I claim is:

1. A relay comprising a vertically disposed backplate of moulded insulating material, a non-' magnetizable bracket secured to said backplate adjacent its upper end and projecting laterally from said backplate, two pole pieces secured to said bracket and having poIe faces disposed on the underside of said bracket, a backstrap secured to the upper ends of said pole pieces, a winding mounted on said backstrap, an armature pivotally attached to said bracket for swinging movement toward and away from the pole faces of said pole pieces, a depending portion formed 1 on said bracket adjacent the free end of said armature, a supporting strap secured to said depending portion, a stop screw adjustably screwed through said strap and cooperating with said armature to limit its movement away from said 1 pole faces, a plurality of movable contact fingers mounted in said backplate, means for operatively connecting said movable contact fingers with said armature, and other contact fingers mounted in said backplate and cooperating with said movable fingers to form contacts.

2. A relay comprising a vertically disposed backplate of moulded insulating material, a nonmagnetizable bracket secured to said backplate adjacent its upper end and projecting laterally from said backplate, two pole pieces secured to said bracket and having pole faces disposed on the underside of said bracket, a backstrap secured to the upper ends of said pole pieces, a winding mounted on said backstrap, an armature pivotally attached to said bracket for swinging movement toward and away from the pole faces of said pole pieces, a depending portion formed on said bracket adjacent the free end of said armature, a supporting strap secured to said depending portion, a stop screw adjustably screwed through said strap and cooperating with said armature to limit its movement away from said pole faces, a plurality of movable contact fingers mounted in said backplate, means for operatively connecting said movable contact fingers with said armature, other contact fingers mounted in said backplate and cooperating with said movable fingers to form contacts, and a transparent cover secured to the depending portion of said bracket and enclosing all of the operating parts of said relay.

3. A relay comprising a backplate of moulded insulating material provided with a raised portion on its forward face and with a recess in its rear face directly back of said raised portion and with a plurality of slots extending through said raised portion and communicating with said recess, said slots being arranged in vertical rows, a plurality of contact fingers each having a portion of reduced width extending through said slots, said fingers being secured within said slots by bending out portions of the edges of the fingers at the rear ends of said slots by means of a swedging tool, a rubber gasket disposed in said recess and provided with openings through which the rear ends of said fingers pass, a clamping plate disposed within said recess behind said gasket, means for securing said clamping plate to said backplate to compress said gasket, whereby the slots through which said fingers pass are sealed at the rear side of said backplate, an electromagnet secured to said backplate, an armature operated by said electromagnet and operatively connected with certain ones of said contact fingers to operate the contacts formed by said fin gers, and a transparent cover clamped against the forward face of said backplate and enclosing all of the operating parts of said relay, whereby all of the operating parts are open to inspection but are protected against damage by foreign substances.

4. A relay comprising a backplate of insulating material, an electromagnet secured to the forward face of said backplate and including a winding wound on a spool of moulded insulating material the head of which is provided with two threaded metal inserts connected respectively with the two ends of the winding, slots provided vided with tail portions which project through said slots and one secured to said inserts by means of screws, whereby electrical connections with said winding may be made by inserting plugs into said connectors.

5. A relay comprising a backplate of insulating material, an electromagnet secured to the forward face of said backplate and including a winding Wound on a spool of moulded insulating material the head of which is provided with two threaded metal inserts connected respectively with the two ends of the winding, slots provided in said backplate directly opposite said inserts communicating with recesses formed .in said backplate directly back of the slots, female connectors secured within said recesses and provided with tail portions which project through said slots and are secured to said inserts by means of screws, whereby electrical connections with said winding may be made by insertingplugs into said connectors, an armature operated by said electromagnet, and contacts mounted on said panel and operatively connected with said armature and provided with portions which extend through said panel and constitute plugs for making electrical contact with saidfingers.

6. The combination with a relay comprising an insulating backplate having an electromagnet secured thereto, an armature operated by said magnet, and contacts mounted on said backplate and operatively connected with said armature and having plug portions disposed on the rear side of said backplate, of a mounting plate having female connectors mounted therein which constitute a plug receptacle for cooperating with the plug portions of said fingers, and means for latching said backplate to said mounting plate comprising a latching member secured to said mounting plate and projecting into a recess in said backplate, and cooperating latch means mounted in said recess and engaging said latch member.

.7. The combination with a relay comprising an insulating backplate having an electromagnet secured thereto adjacent its upper end, an armature operated by said magnet and disposed below said magnet, and contacts mounted on said backplate below said armature and having plug pertions extending into a recess formed in the rear side of said backplate, of an insulating mounting plate having a raised portion adapted to fit into said recess and provided in said raised portion withslots for the reception of the plug portions of said fingers and with recesses directly in back of said slots, female connectors secured within the recesses in said mounting plate and cooperating with the plug portions of said contacts to make contact therewith, and latch means for securing said backplate to said mounting plate comprising a latch member mounted in said\ mounting plate opposite said electromagnet and extending into a recess in said backplate and cooperating with means mounted in said recess for engaging said latch member.

8. The combination with a relay comprising an insulating backplate having an electromagnet secured thereto adjacent its upper end, an armature operated by said magnet and disposed below said magnet, and contacts mounted on said backplate below said armature and having plug portions extending into a recess formed in the rear side of said backplate, of an insulating mounting plate having a raised portion adapted to fit into said recess and provided in said raised portion with slots for the reception of the plug portions of said fingers and with recesses directly in back of said slots, female connectors secured within the recesses in said mounting plate and cooperating with the plug portions of said contacts to make contacttherewith, a latch member secured to said mounting plate opposite said magnet and projecting into a recess in said backplate and provided within said recess with a conical head forming an annular shoulder, a latch spring mounted in the recess in said backplate and having two arms biased toward each other in position to engage said latch member at said shoulder, a vertical rod' extending into' said recess and biased to one position, and means secured to said rod and cooperating with said arms to spread said arms to positions to clear the head of said latch member in response to movement of said rod away from its biased position.

9. The combination with a relay comprising an insulating backplate having an electromagnet secured thereto adjacent its upper end, an armature operated by said magnet and disposed below said magnet, and contacts mounted on said backplate below said armature and having plug portions extending into a recess formed in the rear side of said backplate, of an insulating mounting plate having a raised portion adapted to fit into said recess and provided in said raised por tion with slots for the reception of the plug portions of said fingers and with recesses directly in back of said slots, female connectors secured within the recesses in said mounting plate and cooperating with the plug portions of said contacts to make contact therewith, a latch member secured to said mounting plate opposite said magnet and projecting into a. recess in said backplate and provided within said recess with a conical head forming an annular shoulder, a latch spring mounted in the recess in said backplate and having two arms biased toward each other in positions to engage said latch member at said shoulder, and means mounted in said backplate and cooperating with said arms for at times spreading said arms to release said latch.

10. A relay comprising a vertically disposed and contacts mounted on said backplate and operatively connected with said armature.

11. A relay comprising a backplate of moulded insulating material provided with a raised portion on its forward face and with a recess in its rear face directly back of said raised portion and with a plurality of slots extending through said raised portion and communicating with said recess, said slots being arranged in vertical rows, a plurality of contact fingers each having a portion extending through said slots, means for securing said fingers within said slots, a rubber gasket disposed in said recess and provided with openings through which the rear ends of said fingers pass, a clamping plate disposed within said recess behind said gasket, means for securing said clamping plate to said backplate to compress said gasket, whereby the slots through which said fingers pass are sealed at the rear side of said backplate, an electromagnet secured to said backplate, an armature operated by said electromagnet and operatively connected with certain ones of said contact fingers to operate the contacts formed by said flngers, and'a transparent cover clamped against the forward face of said backplate and enclosing all of the operating parts of said relay, whereby all of the operating parts are open to inspection but are protected against damage by foreign substances.

BRANKO LAZICH. 

